proof of work [English]

Syndetic Relationships

InterPARES Definition

No definition in earlier IP projects. ITrust definition not yet developed.

Other Definitions

  • Bitcoin Developer Glossary 2017 (†791 s.v. "Proof of Work"): A hash below a target value which can only be obtained, on average, by performing a certain amount of brute force work—therefore demonstrating proof of work.
  • Bitcoin Glossary 2017 (†812 s.v. "Proof of work"): A system that ties mining capability to computational power. Blocks must be hashed, which is in itself an easy computational process, but an additional variable is added to the hashing process to make it more difficult. When a block is successfully hashed, the hashing must have taken some time and computational effort. Thus, a hashed block is considered proof of work.
  • Bitcoin Group [2017] (†846 s.v. "Proof of work"): A system that ties mining capability to computational power. Blocks must be hashed, which is in itself an easy computational process, but an additional variable is added to the hashing process to make it more difficult. When a block is successfully hashed, the hashing must have taken some time and computational effort. Thus, a hashed block is considered proof of work.
  • Bitcoin Wiki Vocabulary [2017] (†796 s.v. "Proof of work"): A proof of work is a piece of data which is difficult (costly, time-consuming) to produce but easy for others to verify and which satisfies certain requirements. Producing a proof of work can be a random process with low probability so that a lot of trial and error is required on average before a valid proof of work is generated. Bitcoin uses the Hashcash proof of work system.
  • Blockchain Technologies 2016 (†789 s.v. "Proof-of-Work"): A system that ties mining capability to computational power. Blocks must be hashed, which is in itself an easy computational process, but an additional variable is added to the hashing process to make it more difficult. When a block is successfully hashed, the hashing must have taken some time and computational effort. Thus, a hashed block is considered proof of work.
  • BlockchainHub Glossary (†807 s.v. "Proof of Work"): POW system/protocol/function is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer. The concept may have been first presented by Cynthia Dwork and Moni Naor in a 1993 journal. The term “Proof of Work” was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels. A key feature of these schemes is their asymmetry: the work must be moderately hard (but feasible) on the requester side but easy to check for the service provider. This idea is also known as a CPU cost function, client puzzle, computational puzzle or CPU pricing function.
  • Scaling Bitcoin [2017] (†845 s.v. "Proof-of-Work / PoW"): In order to be accepted by the rest of the network, a new block must contain a so-called proof-of-work.[50] The proof-of-work requires miners to find a number called a nonce, such that when the block content is hashed along with the nonce, the result is numerically smaller than the network's difficulty target. This proof is easy for any node in the network to verify, but extremely time-consuming to generate, as for a secure cryptographic hash, miners must try many different nonce values (usually the sequence of tested values is 0, 1, 2, 3, … before meeting the difficulty target.
  • Wood 2014 (†803 p.2): Mining is the process of dedicating effort (working) to bolster one series of transactions (a block) over any other potential competitor block. It is achieved thanks to a cryptographically secure proof. This scheme is known as a proof-of-work...

Citations

  • Buterin [2017] (†818 s.v. "History"): In 2009, a decentralized currency was for the first time implemented in practice by Satoshi Nakamoto, combining established primitives for managing ownership through public key cryptography with a consensus algorithm for keeping track of who owns coins, known as "proof of work." (†2114)
  • Piasecki 2017 (†815 s.v. 2017-02-20 "Blockchain Terminology-a dev): · Proof of Work is a Block creation algorithm that uses a Hashing algorithm to ensure predictable Block creation rate. It relies on the fact that a Hash of a Block is essentially a very large random number, and that it takes some computational time to create the Hash. While it might take a fraction of a second to create one Hash, having to create a lot of Hashes takes a significant amount of time and resources. · A valid Block has a Hash smaller than a given Target (see Difficulty). To create a Hash that satisfies that criteria, the Miner needs to compute many potential Hashes until they find a satisfactory one. Since Hashes are essentially random numbers, it is easy to approximate how many times one would need to compute a Hash to get one that is small enough. · As more Miners join the network with more powerful Mining machines, they naturally can compute more Hashes in the same amount of time. The Proof of Work algorithms are designed to handle that by making it harder to compute a valid Hash by lowering the Target more and more. If the Miners leave the network and the available computational power decreases, the Target increases to maintain the Block creation speed. · Another important design of the Proof of Work algorithm is that it takes a lot of computational power to create a valid Hash, but very little to verify it (one needs to hash the data once). · Proof of Work is used to secure the Blockchain Network from attackers trying to subvert it (they would need to have a lot of spare computing power), as well as to create a fair distribution model for the Coins (Miners are rewarded with newly minted Coin for creating a valid Block). (†2105)
  • Wood 2014 (†803 p.1): Five years later, Nakamoto [2008] introduced another such proof-of-work-secured value token, somewhat wider in scope. The fruits of this project, Bitcoin, became the first widely adopted global decentralised transaction ledger. (†2072)